The present invention relates to surgical methods and prosthetic devices for ameliorating hearing loss in patients suffering from ailments of the middle ear.
Chronic otitis media (COM), a common inflammatory disease of the middle ear and mastoid, can affect 0.5 to 30% of the population (a conservative estimate of the number of people suffering from COM is over 5 million in the U.S. and over 120 million worldwide), and results in conductive hearing loss that can range in severity up to 60 dB. The main form of therapy for COM is surgical, i.e., mastoidectomy and tympanoplasty. Although tympanomastoid surgery is typically successful in controlling infection, a post-operative hearing loss of more than 20 dB persists in about 50% of patients. Such hearing loss is often significant, in the range of 40 to 60 dB. Non-aeration of the middle ear due to deposition of fibrous tissue or formation of fluid resulting from eustachian tube dysfunction is understood to be the main cause of such post-operative hearing loss.
Serous otitis media (OME) is another common disorder of the middle ear that can lead to conductive hearing loss ranging in severity up to 30-40 dB. A number of patients with OME fail to respond to medical therapy and hence require surgical intervention by way of a tympanostomy (ventilation) tube. In fact, tympanostomy tube placement is the most common operation performed in the United States, with over 1.3 million ears intubated annually. Such tubes, however, have several disadvantages that include the need for water precautions, and the potential for chronic perforations, focal tympanic membrane atrophy, formation of retraction pockets, cholesteatoma and tube extrusion.
The introduction of a small bubble of gas into the middle ear of patients with eustachian tube obstruction, in which the middle ear and mastoid are filled with serous fluid, improves the conductive hearing loss of such patients as long as the air bubble remains in the middle ear. This has led some investigators to inject air or other gases in the middle ear to improve hearing loss. Such gases, however, are short-lived in the middle ear due to absorption. Further, attempts to create long-lasting air pockets using silicone elastomers or an air-filled hollow body of silastic have failed to produce lasting benefit, presumably because of extrusion of the prosthesis and/or failure of the prosthesis to remain inflated.
U.S. Pat. No. 5,356,430 of Nadol describes a hearing prosthesis that is deemed to provide relief from hearing loss under certain conditions.
It is thus an object of the invention to provide prolonged relief from conductive hearing loss caused by ailments of the middle ear.
It is another object of the invention to provide a surgical method for ameliorating hearing loss caused by ailments of the middle ear.